Generally two-pole generator rotors utilized in IDG's, APU's etc. are composed of a plurality of precision fitted parts which are bolted or welded together. While this technical approach is functionally satisfactory, a disadvantage of this approach resides in the fact that the total costs involved in producing the rotor as a result of the required precision fitting of the components as well as the necessary welding and bolting operations is relatively high. Conventionally, to accommodate a large number of turns in a field coil of a generator, wedge portions are provided which accommodate the field coil, with the wedges being generally hollowed out or configured to a coil profile which is somewhat rounded. This shaping requires complex parts for the retention of the end turns and high strength bolts are utilized to bolt shaft ends to the field coil pole piece and retain the separate field core accommodating wedges to the field pole pieces. Additionally, for a torque transmission, the oil accommodating canister surrounding the field coil is welded to the ends of the shaft after assembly and then finish ground to size.
A disadvantage of the conventional approach resides in the fact that the completed unit is, at best, difficult if not impossible to repair or service and, taking into account the manufacturing steps and processes, the unit is difficult and expensive to construct.
Furthermore, by virtue of the welding of the oil accommodating canister to the ends of the shafts, the conventional two-pole generator rotors are more or less somewhat disposable units since to repair or service such units, it is necessary to cut the welds so as to enable a removal of the oil accommodating canister which, as can readily be appreciated, is an expensive and time consuming process.
Typical examples of rotor constructions of the aforementioned type are disclosed in, for example, U.S. Pat. Nos. 4,510,679, 4,562,641, 4,591,749, 4,757,603, 4,674,178, 4,625,135, 4,590,218, 4,591,749, 4,598,218 and 4,614,888. While each of these patents provide various approaches for constructions of rotors and/or rotor assemblies, each of the technical approaches suffer from one or more of the above noted disadvantages encountered in the prior art.
More particularly, in U.S. Pat. No. 4,591,749 an arrangement is proposed for securing magnets to a shaft disposed beneath such magnets, with the shaft extending axially and protruding from each end of a magnetic portion of the assembly. This approach utilizes a plastic cage creating pockets or cavities for enabling an emplacement of a plurality of magnets, with a cover being staked to the end of the cage to retain the magnets in place.
In U.S. Pat. No. 4,625,135, an arrangement is provided for retaining magnets to a throughshaft by utilizing a shrink fit, with the functional significance lying in a provision of an arrangement for transferring the heat away from the magnets by utilizing a cast-in place aluminum heat sink which also functions to simplify installation of the magnets by providing pockets for accommodating such magnets.
The same is true with regard to U.S. Pat. No. 4,674,178 wherein several magnets are attached to a hub or shaft and retained in place by an encapsulation compound between the magnets and a fiber/resin matrix wrapped radially about the magnets. U.S. Pat. No. 4,757,603 proposes a sheet metal fabrication which spaces the individual magnets and retains the same with bent tabs, with the retention of the plurality of magnets being achieved by using an adhesive or a moldable matrix, and with the shaft being axially inserted through the assembly and retained by the molded matrix.
In aforementioned U.S. Pat. No. 4,562,218, a sleeve is joined by welding, with the ends of the shaft being welded to a canister, and wedges being provided and bolted to the core, with the end shafts also being bolted to the core.
While aforementioned U.S. Pat. No. 4,562,641 provides for a joining of end shafts to a rotor sleeve so as to achieve a rigid structure, the entire approach relates to a sequentially constructed rotor with the method of assembly of the end shafts being achieved by a plurality of fastening means such as bolts.